The present invention relates to a unit for packaging products.
In particular, the invention relates to a unit for packaging elements of elongated appearance, typically cigarettes, in packets of the rigid type with a hinged lid, to which direct reference will be made in the present specification albeit with no limitation in scope implied.
Generally considered, cigarette packets of the rigid type with a hinged lid are of substantially rectangular parallelepiped shape and comprise a container, of cupped embodiment, surmounted by a similarly cupped lid hinged to a rear top edge of the container and rotatable thus between an open position and a position in which the container is closed.
The single packet is fashioned generally from a flat diecut blank of substantially rectangular outline referable to a predominating longitudinal axis, presenting two longitudinal crease lines and a plurality of transverse crease lines combining to define a front panel, an end panel and a rear panel compassed between the two longitudinal lines, both for the container and for the lid.
The blank also presents lateral portions that are bent along the aforementioned longitudinal crease lines to form respective side panels constituting the flank faces of the packet.
Packers of conventional design, the machines by which groups of cigarettes are wrapped in rigid packets of the type outlined briefly above, will generally comprise a wrapping wheel rotatable about a substantially horizontal axis and presenting a plurality of peripheral seats by which the blanks are taken up in succession at an infeed station together with the groups of cigarettes, these being ordered previously and wrapped normally in metal foil paper.
In accordance with one wrapping method, each of the aforementioned blanks is placed in the relative seat and advanced along a substantially circular feed path through a succession of stations at which the blank is folded by steps around the relative group of cigarettes.
Thereafter, at an outfeed station of the wrapping wheel, the single blank and the corresponding group of cigarettes partially enveloped by the blank are aligned with gripping elements distributed around the periphery of a transfer wheel disposed with its axis parallel to the axis of the wrapping wheel and rotating in the opposite direction. The function of the transfer wheel is to take up each blank along with the group of cigarettes and, following a given angular movement of the gripping element about a radial axis, to place the partly assembled pack on respective receiving elements afforded by a belt conveyor. The conveyor directs the assembled blanks and groups of cigarettes along a path parallel to the predominating axis of the blank toward a gluing station, a further station at which the lateral portions are folded, and a station from which the completed packets run out.
In particular, the flank faces of the packet are folded by fixed helical elements, located on either side of the belt conveyor in such a manner as to engage and flatten the respective lateral portions of the blank one over the other as the blank and the group of cigarettes advance together along the path followed by the belt conveyor. This means also that an appreciable force must be applied by the fixed helical folders in a direction perpendicular to the flattened lateral portions so that their breasted surfaces will bond after a predetermined quantity of adhesive substance has been interposed between these same surfaces at the gluing station. In effect, the adhesives employed are reasonably quick setting, although not instantaneous, and accordingly there is the need for a substantially uniform pressing action to be exerted on the flank faces of the packet for a given duration.
The fixed helical folders mentioned above betray certain drawbacks.
A first drawback connected with the use of fixed helical folders consists in the fact that there is relative sliding contact between the folders and the packet advancing on the conveyor, also that notable frictional forces are generated between the flank faces and the folders not least as a result of the aforementioned force applied perpendicularly to the flank faces. Besides tending to impede the free movement of the packets along the conveying path, the sliding action and frictional forces can damage the outer surface of the packets through the effects of scoring and rubbing or abrasion.
A second drawback connected with the use of fixed folders, attributable likewise to the perpendicular force applied to the lateral portions of the blank when overlapped to form the flank faces, is that a part of the adhesive substance interposed between these same portions can be forced out. Thus one has residues of adhesive that cling to the surface of the fixed folder, inhibiting the smooth advance of the packets along the conveying path and soiling the outer surface of the finished packet.
It will be evident that in order to remove the aforementioned residues of adhesive and clean up the folder, the machine must be shut down, and this in turn brings disadvantages in terms of costs and lost production.
Another drawback connected with the use of fixed folders is that of the impact which occurs between the folders and the advancing semi-finished packet due to the high velocity of relative motion between the two as the product and the enveloping blank are propelled forward by the belt conveyor.
The prior art embraces belt type folders arranged along the conveying path followed by the blanks, of which the function is to bend the blanks and cause them to assume configurations determined by special crease lines.
Such belt type folders on the other hand present the drawback that they do not allow overlapped portions of the blank to be pressed together.
The object of the present invention is to provide a unit for packaging products in rigid packets, such as will be free of the drawbacks mentioned above.
The stated object is realized according to the present invention in a unit for packaging products in respective diecut blanks designed to generate packs of substantially parallelepiped appearance, wherein at least one edge portion of the blank is folded in such a way as to establish a respective face of the pack.
The unit disclosed comprises means by which to fold the edge portion as the products advance along a predetermined folding path in a predetermined direction, also runner means forming part of the folding means, capable of movement in a direction concurrent with that of the advancing products and disposed in contact with the edge portion of the blank during the course of the folding step.